PSQI: Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI) is a 19-item self-report questionnaire that measures sleep quality and disturbances over the past month. Seven component scores sum to a global score of 0 to 21, and a global score above 5 marks poor sleep ^[1].

What does the PSQI measure?

The PSQI is one of the most widely used clinical tools for assessing sleep quality. Developed by researchers at the University of Pittsburgh in 1989, it measures subjective sleep quality over the past month across seven components ^[1].

The 19 self-rated items generate scores for seven components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Each component is scored 0-3, with the sum producing a global score ranging from 0-21.

A global PSQI score greater than 5 indicates "poor sleep quality" with high sensitivity and specificity for distinguishing good and poor sleepers ^[1]. A later review found strong reliability and validity across a range of clinical and non-clinical samples ^[2]. It is often used beside measures of depression, anxiety and PTSD, where poor sleep is common.

Screening tool, not diagnostic

The PSQI identifies poor sleep quality and its likely contributing domains. A full clinical evaluation — often including sleep studies — is required for definitive diagnosis of specific sleep disorders such as insomnia disorder or obstructive sleep apnea.

Copyright and licensing

The PSQI is owned by the University of Pittsburgh. It may be reprinted free only for non-commercial research and educational purposes; clinical and commercial use requires a paid licence from the University. It may not be modified without written permission.

How do you give the PSQI?

Self-report format

Clients complete the 19-item questionnaire independently, reflecting on their sleep patterns over the past month. It can be given in the clinic or remotely.

Administration time

Typically takes 5-10 minutes to complete. Scoring requires calculating seven component scores and summing for a global score (0-21).

Regular monitoring

Administer at intake and every 4-8 weeks during sleep treatment. The one-month timeframe makes monthly reassessment appropriate for tracking progress.

Instructions ask respondents to consider their sleep over the past month, providing a detailed view of sleep patterns rather than isolated nights.

Administration best practices

• Ensure clients understand the "past month" timeframe before starting
• Review component scores, not just the global score, to target specific sleep issues
• Combine with sleep diaries for detailed real-time sleep tracking
• Consider referral to sleep specialists if PSQI > 10 with severe daytime impairment

How do you score and interpret the PSQI?

Seven component scores

Each component is scored 0–3 (0 = no difficulty, 3 = severe difficulty). The sum of all seven component scores yields the global PSQI score (range 0–21). Higher scores reflect worse sleep quality.

Component breakdown

Global PSQI score > 5 indicates poor sleep quality (sensitivity 89.6%, specificity 86.5%) ^[1].

Reconstructing a typical night

Items 1–4 together reconstruct a typical night's sleep pattern: the client records their usual bedtime (item 1), how long it takes to fall asleep (item 2, used in Component 2), the time they wake up (item 3), and the actual hours of sleep obtained (item 4). From these, habitual sleep efficiency (Component 4) is calculated as:

Sleep efficiency (%) = (hours of actual sleep ÷ hours in bed) × 100

For example, a client who goes to bed at 11 pm, takes 45 minutes to fall asleep, sleeps 5.5 hours, and rises at 7 am has spent 8 hours in bed, for a sleep efficiency of 69% (5.5 ÷ 8), using the original scoring formula ^[1].

Low sleep efficiency is a key target in cognitive behavioural therapy for insomnia (CBT-I).

Areas to address

Reviewing component scores alongside the global score directs treatment. The following guide links high component scores to evidence-based intervention targets:

Clinical tip: Review individual component scores at every reassessment, not just the global score. Two clients can both score 9 with entirely different profiles — and entirely different intervention priorities.

Monitoring treatment response

Track global and component scores over time to demonstrate intervention effectiveness — for example, a falling sleep latency component after stimulus control therapy, or a declining sleep medication component during a supervised taper. A meaningful reduction in global score, sustained across repeated administrations, provides the most useful signal of treatment response.

When to refer

Consider sleep specialist referral if:

• PSQI > 10 despite evidence-based behavioural interventions (a widely used clinical convention, not a validated severity tier)
• High sleep disturbance score combined with reported snoring or gasping (possible obstructive sleep apnea)
• Severe daytime dysfunction affecting occupational or social functioning

Psychometric properties

In the original validation ^[1], the PSQI was assessed over 18 months in 52 healthy "good" sleepers and "poor" sleepers (54 adults with depression and 62 with sleep disorders). It showed acceptable internal homogeneity, test-retest reliability and validity, and a global score greater than 5 yielded a sensitivity of 89.6% and specificity of 86.5% (kappa = 0.75) in distinguishing good and poor sleepers.

A 2016 systematic review and meta-analysis of 37 studies found good internal consistency, strong reliability and validity, and moderate structural validity across clinical and non-clinical samples, although factor analytic studies disagreed on the PSQI's structure ^[2].

Limitations

• Screening, not diagnosis. The PSQI cannot diagnose a specific sleep disorder such as insomnia disorder or obstructive sleep apnea.
• Subjective report. It captures perceived sleep, which can differ from objective sleep measured by actigraphy or polysomnography (for example, in paradoxical insomnia).
• One-month recall. Responses depend on recall over the past month, so it is less suited to tracking night-to-night change than a sleep diary.
• Structure. Factor analytic studies disagree on whether the global score reflects one dimension, so component scores should be reviewed alongside the total.
• The >10 referral threshold is a convention. Only the >5 cutoff comes from the original validation.

How does the PSQI compare with other sleep measures?

Different sleep assessment tools measure different aspects of sleep health. Understanding these differences helps you select the right tool for your clinical goals.

PSQI vs ISI: sleep quality vs insomnia severity

The PSQI is a broad-spectrum sleep assessment: use it when you need a full picture of sleep health across multiple dimensions. The ISI is focused on insomnia symptoms and their impact; use it for insomnia screening and for monitoring response to CBT-I (cognitive behavioural therapy for insomnia).

• Vague complaints or any sleep disorder: start with the PSQI.
• Clear insomnia: the ISI is faster and more focused on treatment change.

When to use PSQI: general sleep screening, multiple sleep concerns, research studies, detailed sleep disorder evaluation, or unclear diagnosis.

PSQI vs ESS: sleep quality vs daytime sleepiness

The PSQI and ESS measure opposite ends of the 24-hour sleep-wake cycle. The PSQI assesses how well a person sleeps at night; the Epworth Sleepiness Scale (ESS) assesses how sleepy they are during the day. They are complementary, not interchangeable.

• PSQI: insomnia-type complaints ("I can't fall asleep," "I wake up frequently").
• ESS: excessive daytime sleepiness, snoring, or suspected sleep apnea, where a high score supports a sleep study referral.

Use both when a client has sleep quality complaints AND daytime sleepiness. A high ESS combined with a high PSQI suggests a disorder such as sleep apnea may be disrupting nighttime sleep and causing daytime fatigue — a pattern that warrants polysomnography (sleep study) referral.

PSQI vs actigraphy: subjective vs objective sleep measurement

The PSQI and actigraphy provide different but complementary information.

• PSQI: captures the person's subjective experience of sleep, which relates directly to quality of life and mental health.
• Actigraphy: provides objective data on sleep-wake patterns, useful when self-report may be unreliable (e.g., cognitive impairment, paradoxical insomnia) or when circadian rhythm data is needed.

A common approach is the PSQI for routine screening and treatment monitoring, adding actigraphy when the diagnosis is unclear, a circadian disorder is suspected, or objective confirmation is needed.

Clients who report poor sleep quality (high PSQI) but show normal sleep patterns on actigraphy may have paradoxical insomnia (sleep state misperception). This mismatch guides treatment toward CBT-I rather than sleep medications.

Documenting PSQI scores in clinical notes

PSQI global and component scores belong in the Objective section of a SOAP or intake note.